KR100806864B1 - paper-feeding apparatus of image forming device and paper-feeding method thereof - Google Patents

Abstract

Disclosed are a paper feeding device of an image forming apparatus for feeding paper and a paper feeding method thereof. The paper feeding apparatus of the image forming apparatus includes a side guide part for guiding and setting the width of a sheet of paper, a rear guide part for guiding and setting a vertical width of a sheet of paper, and first and second sheets for simultaneously or separately loading sheets of paper. A paper feed cassette having a stacking unit; A first elevating unit provided in the paper feed cassette and elevating the first loading unit; A second elevating unit installed in the paper feed cassette and raising and lowering the second loading unit; A paper feeder including a pickup roller which picks up and feeds sheets of paper loaded in the first stacker one by one when the first stacker is lifted up; A paper transfer unit installed in the paper feed cassette and transferring the paper loaded in the second loading unit to the first loading unit; And a paper detecting unit detecting whether paper is loaded on each of the first and second loading units, and whether the paper is loaded on the first and second loading units at the same time. The paper conveying portion is controlled to elevate at least one of the first and second loading portions according to whether the paper is loaded simultaneously with the first and second loading portions, and the paper conveying portion loads paper for each of the first and second loading portions. It is characterized in that it is controlled to transfer the paper loaded in the second loading portion to the first loading portion depending on the presence or absence.

Paper cassette, paper, transfer, stacking, lifting

Description

Paper-feeding apparatus and image-feeding method of the image forming apparatus

1 is a partially cutaway perspective view of a conventional paper cassette.

2 is a perspective view of a paper feeding apparatus of the image forming apparatus according to the present invention;

3A and 3B are side views illustrating the operation of the pickup roller lifting unit of the paper feeding unit of the paper feeding device shown in Fig. 2;

FIG. 4 is a partial sectional view illustrating the operation of the first and second lifting units of the paper feeding device shown in FIG. 2 when paper is simultaneously loaded in the first and second loading portions. FIG.

Fig. 5 is a partial sectional view illustrating the operation of the first and second lifting units of the paper feeding device shown in Fig. 2 when the paper is separately loaded in the first and second loading portions.

6A and 6B are perspective views of a first one-way power transmission unit of the second lifting unit of the paper feeding device shown in Fig. 2;

7A and 7B are perspective views illustrating the operation of the first loading unit paper detection sensor of the paper detection unit of the paper feeding device shown in Fig. 2;

8A and 8B are perspective views illustrating the operation of the second loading unit paper detection sensor of the paper detection unit of the paper feeding device shown in Fig. 2;

9A, 9B and 9C are perspective views illustrating the operation of the separ rate sensor of the sheet detection unit of the sheet feeding apparatus shown in Fig. 2;

10 is a flowchart illustrating a process of a paper feeding method of an image forming apparatus according to the present invention.

* Description of the symbols for the main parts of the drawings *

100: paper feeder 112: paper feed cassette

113: paper feed unit 113a: pickup roller assembly

114: pickup roller 117, 200: drive motor

130, 263, 266: position sensor 140: pickup roller lifting unit

150: side guide portion 151, 154: side guide

159: interlocking operation portion 161, 168: loading portion

161, 169: Paper plate 174, 183: Lifting unit

175, 184: lifter 176, 179, 185, 195: lifting plate

189, 198, 219: one-way power train 214: paper feed unit

235: rear guide portion 236: rear guide

244: paper detection unit 245: width detection sensor

249: vertical width detection sensor 253: first loading unit paper detection sensor

259: second loading paper detection sensor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine, and the like, and more particularly, to a paper feeding apparatus of an image forming apparatus for feeding paper and a feeding method thereof.

In general, an image forming apparatus such as a printer, a copier, or the like includes a paper feed cassette for loading a plurality of sheets of paper that can be used for image formation. The paper feed cassette is usually detachably or slidably installed in the main body such that the whole is taken out to the outside or a part is taken out to the outside during paper feeding or replacement.

These paper cassettes are divided into dedicated cassettes that can only use paper of a single size, and universal cassettes that can freely use different sizes of paper by adjusting the paper size according to the size of paper. .

Dedicated cassettes have the advantage that the paper size is fixed according to the size of one paper, so that the paper can be fed with certainty. However, when using different sizes of paper, the cassette must be replaced with the corresponding cassette. Since the cassettes must be prepared, the total number of cassettes increases, and there is a need to secure a place for storing the cassettes used separately.

Therefore, recently, there is a trend to use a universal cassette capable of using a plurality of sizes of paper in one cassette.

Referring to Figure 1, the user adjusts the width of the paper, that is, the side guide portion for guiding and setting the paper in the horizontal direction and the vertical width of the paper, that is, the rear guide portion for guiding the paper in the longitudinal direction to adjust the various types of paper A general universal cassette 1 is shown which can be loaded.

The universal cassette 1 is coupled to the case 10 and both sides of the case 10 by pins 13 so as to be rotated up and down, and a knock-up plate 12 and a knock-up plate on which the paper is seated on the upper surface thereof. 12) a side guide portion 14 having a pair of side guides installed in the case 10 so as to slide in the horizontal direction of the paper while supporting the side edges of the paper seated on the sheet 12, the paper seated on the knock-up plate 12 The knock-up plate is guided by the rear guide part 16 and the side guide part 14 and the rear guide part 16 installed in the case 10 to move the serration in the longitudinal direction of the paper while supporting the rear end of the sheet. And a pair of finger members 17 for crimping and supporting the leading edge portion of the sheet seated at 12.

The lower portion of the knockup plate 12 is provided with a spring 18 for pressing the knockup plate 12 upward. In addition, the side guide portion 14 is provided with a rack 15, respectively, the pinion (not shown) is engaged between the rack 15 and the side guide portion 14 to guide the sliding movement of the side guide portion (14). do.

Looking at the paper supply or the paper replacement operation of the conventional universal cassette (1) configured as described above, as follows.

First, the universal cassette 1 mounted on the main body of the image forming apparatus is separated from the mounting position of the main body so that paper can be supplied or replaced, and is taken out to the outside, or is removed from the mounting position of the main body and moved to expose a part to the outside. do.

Subsequently, the side guides of the side guide portion 14 are adjusted to be sufficiently spaced so as to feed or replace the paper, and then new paper is loaded on the knock-up plate 12, or previously loaded paper is replaced with new paper. .

After the paper is loaded or replaced, the side guide portion 14 is moved in the direction of the arrow I to closely support the paper from the side. The rear guide portion 16 is also moved in the direction of the arrow (H) to support the rear end of the paper.

At this time, the leading end of the paper is adjusted to coincide with the leading end of the knockup plate 12, and the leading end of the paper is interposed between the knockup plate 12 and the finger member 17.

In this way, the loaded paper waits in a state of being pressed against the finger member 17 by the elastic force of the spring 18 installed on the lower portion of the knock-up plate 12.

Then, the universal cassette 1 on which the paper is loaded is mounted on the main body again.

However, such a conventional universal cassette 1 is arranged such that the rear guide portion 16 is moved by the user to perform a simulation movement. Therefore, when the rear guide portion 16 is moved to set paper of a different size, the rear guide portion 16 16) has a problem that is not easily adjusted.

In addition, when the conventional universal cassette 1 loads paper smaller than the maximum size of paper that can be loaded in the cassette, for example, half size paper, the conventional cassette 1 does not utilize even if a free space occurs at the rear of the loaded paper. There was a problem leaving it blank. That is, when extra paper is loaded in the free space formed at the rear end of the loaded paper, and the paper is used up, the paper loaded in the free space is automatically supplied, and the paper loaded in the cassette is consumed to supply additional paper. If this is necessary, the cumbersome operation of feeding paper by adding a cassette can be avoided. However, this is not possible with the conventional universal cassette 1.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is not only to easily load various sizes of paper, but also to increase the amount of paper loading. To provide a way.

The paper feeder of the image forming apparatus according to the embodiment of the present invention for achieving the above object of the present invention, the side guide portion for guiding and setting the width of the paper, the rear guide for guiding and setting the vertical width of the paper A paper feed cassette having a portion and first and second loading portions capable of simultaneously or separately loading paper; A first elevating unit provided in the paper feed cassette and elevating the first loading unit; A second elevating unit installed in the paper feed cassette and raising and lowering the second loading unit; A paper feeder including a pickup roller which picks up and feeds sheets of paper loaded in the first stacker one by one when the first stacker is lifted up; A paper transfer unit installed in the paper feed cassette and transferring the paper loaded in the second loading unit to the first loading unit; A paper detecting unit for detecting whether paper is loaded on each of the first and second loading units, and whether paper is loaded on the first and second loading units at the same time; And controlling the first and second lifting portions so as to lift at least one of the first and second loading portions according to whether paper is simultaneously loaded in the first and second loading portions, And a control unit for controlling the paper transfer unit to transfer the paper loaded in the second loading unit to the first loading unit according to whether the paper is loaded on each of the two loading units.

The control unit controls to raise and lower both the first loading portion and the second loading portion when paper is simultaneously loaded in the first and second loading portions, and the paper is separately loaded in the first and second loading portions. When the paper is loaded only in the second loading portion, it is preferable to control to move the paper loaded in the second loading portion to the first loading portion. .

The side guide part may include a first and second side guides for supporting and guiding both side edges of the paper in the first loading part, and an interlocking operation part for operating the first and second side guides in conjunction with each other. The interlocking operation portion is rotatably installed in the paper feed cassette between the first rack formed in the first side guide, the second rack formed in the second side guide, and the first and second racks, and engaged with the first and second racks. It is preferred to consist of a pinion.

The first and second stacking portions may be constituted by first and second paper stacking plates, which are installed to be able to elevate to the first and second positions in the paper feeding direction downstream and upstream, respectively, and can stack the paper. Here, the first position is a position where the first and second paper loading plates are lowered to load paper, and the second position is such that the first and second paper loading plates can contact the pickup roller of the paper feeder. Elevated position.

The first lift unit includes a first lifter for elevating the first loading unit to the first and second positions, a first position sensor for detecting the first position of the first loading unit, and a second position for detecting the second position of the first loading unit; It can be configured as a tooth sensor.

The first lifter includes: a first lifting plate having a first driving motor, a first power transmission shaft having a first corresponding coupling connected to a first coupling formed at a first driving shaft of the first driving motor at one end; It is preferable that the second lifting plate is provided with a second power transmission shaft having a second gear engaged with the first gear formed on the first power transmission shaft. In addition, the first position sensor is composed of a first sensing member formed in the paper feeding portion, and a first sensor portion provided to face the first sensing member so as to detect the operation of the first sensing member, and the second position sensor is provided in the first loading portion. Preferably, the formed second sensing member and a second sensor unit provided in the paper feed cassette to face the second sensing member so as to detect the operation of the second sensing member.

Optionally, the first lifting part may further include a first plate guide for guiding the movement of the first loading part. The first plate guide is provided with at least one pair of first and second rollers respectively provided to be rotatable on both sides of the first loading part in the feeding direction, and at least one pair of the first and second rollers respectively formed in the paper cassette opposite to the first and second rollers. It is preferred that the first and second guide grooves.

The second lifting unit may be configured as a second lifter for elevating the second loading unit to the first and second positions. The second lifter includes a third power transmission shaft including a second driving motor and a second corresponding coupling coupled to a second coupling coupled to the second driving shaft and the first driving portion of the second driving motor. And a fourth lifting plate having a third lifting plate and a fourth power transmission shaft having a fourth gear engaged with the third gear installed on the third power transmission shaft. Here, the second lifter may include the third and fourth gears and the third and fourth gears so that the rotational forces of the third and fourth gears are transmitted to the third and fourth power transmission shafts only when the second driving motor rotates in one direction, respectively. It is preferable to further include a first and second one-way power transmission unit respectively provided between the fourth power transmission shaft.

Optionally, the second lifting part may further include a second plate guide for guiding the movement of the second loading part. The second plate guide is formed of at least one pair of third and fourth rollers and at least one pair of first rollers respectively formed in the paper feed cassette opposite to the third and fourth rollers respectively installed to be rotatable on both sides of the second loading portion in the feeding direction. It is preferable that the third and fourth guide grooves are configured.

The paper transfer part includes a transfer member for transferring the rear guide part so that the paper loaded in the second loading part is moved to a position where the paper is loaded in the first loading part, and a third position sensor for detecting the position of the rear guide part carried by the transfer member. Can be configured. The conveying member has a fifth power transmission shaft having a third corresponding coupling coupled to a third coupling coupled to a second driving shaft of the second driving motor via a second power transmission portion at one end thereof, and a rear guide portion for feeding paper. A linear motion conversion unit for converting the rotational force of the fifth power transmission shaft into a linear motion to be reciprocated in the direction to transfer to the rear guide portion, and a second guide portion for guiding the movement of the rear guide portion. Here, the transfer member is formed between the third corresponding coupling and the fifth power transmission shaft so that the rotational force of the third corresponding coupling is transmitted to the fifth power transmission shaft only when the second driving motor rotates in the other direction. It may further include a three-way power transmission unit.

The linear motion converting portion is composed of a timing belt including at least one driving pulley formed on the fifth power transmission shaft, a driven pulley installed on the paper feed cassette, and a corresponding gear portion connecting the driving pulley and the driven pulley and engaged with the gear portion of the rear guide portion. It is desirable to be.

The third position sensor is composed of a third sensing member formed in the rear guide portion, and a third sensor portion provided in the paper feed cassette and provided to face the third sensing member so as to detect the operation of the third sensing member.

The paper detection unit, a width detection sensor for detecting the width of the plurality of sheets, a vertical width sensor for detecting the vertical width of the plurality of sheets, a first loading unit paper detection sensor for detecting the presence or absence of paper loading of the first loading unit, and And a second loading part paper sensor for detecting the presence or absence of paper loading in the second loading part. The width detecting sensor includes a first switch having a first operating member formed under the side guide part, and a first switch having a plurality of switching terminals formed in a movement path of the first operating member in the paper feed cassette. The vertical width sensor comprises a second switch having a second operating member formed under the rear guide portion, and a second switch having a plurality of switching terminals formed on the paper feed cassette in the movement path of the second operating member. The first loading unit paper detection sensor includes a first sensing hole formed in the first loading unit, a first end formed in a frame of the main body, and received or blocked in the first sensing hole by its own weight according to whether paper is loaded. And a fourth sensor unit provided opposite the second end of the fourth sensing member to detect the operation of the fourth sensing member and the fourth sensing member. The second loading part paper sensor is formed in the second sensing hole, the paper feed cassette formed in the second loading part, and has a first end projecting outward or descending down through the second sensing hole by the weight of the paper. And a fourth sensor portion provided opposite the second end of the fifth sensing member to detect the operation of the fifth sensing member and the fifth sensing member.

Optionally, the paper detection unit may further include a separate sensor that detects the vertical width of the paper that the vertical width detection sensor cannot detect. The separate sensor includes a rotating member pivoted near the second loading portion of the paper cassette so that a portion thereof protrudes into the paper loading space of the second loading portion, a sixth sensing member protruding from the rotating member, and a sixth sensing member of the rotating member. And a sixth sensor unit provided opposite the sixth sensing member so as to detect the sixth sensing member. At this time, in order to prevent the paper loaded in the second loading portion from being caught by the separate sensor when the paper transfer portion transfers the paper loaded in the second loading portion to the first loading portion, the separate sensor may include the paper transfer portion in the second loading portion. And a solenoid for rotating the rotating member such that a portion of the rotating member protruding into the paper loading space of the second loading portion moves out of the paper loading space of the second loading portion when the paper loaded in the loading portion is transferred to the first loading portion. Can be.

A paper feeding method of an image forming apparatus according to another embodiment of the present invention comprises the steps of: determining whether paper is loaded simultaneously with the first and second loading portions, and whether paper is loaded together with the first and second loading portions. And raising at least one of the first and second loading portions from the first position to the second position depending on the presence or absence, and picking up paper through the sheet feeding portion and feeding the sheets into the image forming apparatus one by one. do.

The step of determining whether the paper is loaded on the first and second loading parts at the same time includes determining whether the width sensor and the height sensor are 'on', and both the width sensor and the height sensor Determining that the paper is simultaneously loaded in the first and second loading parts when it is determined to be 'on', and when the width sensor is judged to be 'on' and the vertical sensor is 'off' It can be carried out by the step of determining that is separately loaded in the first and second loading portion. Optionally, the step of determining whether the paper is loaded on the first and second loading parts at the same time may include a width detecting sensor, a vertical width detecting sensor, and a second loading paper detecting sensor in order to determine a larger size paper. And determining whether the separate sensor is 'on', at least one of the vertical width sensor, the second loading part paper sensor, and the separate sensor, and when the width detection sensor is determined to be 'on'. Determining that the paper is loaded simultaneously with the second loading part, and when the second loading part paper sensor, the separate sensor, the width detection sensor, or both are determined to be 'on', the paper is loaded with the first and second loading parts. It may be performed as a step of determining separately loaded in.

The step of determining whether the paper is loaded on the first and second loading parts simultaneously determines whether the paper is loaded on the first and second loading parts when it is determined that the paper is separately loaded on the first and second loading parts. It may further comprise a step. The step of determining whether the first and second loading portions have paper loading includes determining that the paper is loaded in the first loading portion when the width detection sensor is determined to be 'on', and the second loading portion paper detection sensor Determining that the paper is loaded in the second loading part when the separate sensor is judged to be 'on', and when determining that the width sensor, the second loading sensor and the separate sensor are 'on' Determining that the paper is loaded in the first and second loading portions respectively, and determining that the paper is not loaded in both the first and second loading portions or is an error when no sensor is 'on'. Can be. The determining that the paper is not loaded or an error may further include warning or displaying that there is no paper or an error on the outside.

Raising at least one of the first and second loading portions from the first position to the second position removes both the first and second loading portions when it is determined that the paper is loaded simultaneously in the first and second loading portions. Raising from the first position to the second position, and raising only the first loading portion from the first position to the second position when it is determined that the paper is separately loaded in the first and second loading portions. . The first position is a position where the first and second loading portions are lowered to load the paper, and the second position is the position where the first and second loading portions are raised so that the paper can contact the pickup roller of the paper feeding portion.

When it is determined that paper is separately loaded in the first and second loading portions, the step of raising only the first loading portion from the first position to the second position may include loading the paper in the first loading portion or the first and second loading portions. Raising the first loading portion from the first position to the second position when judged to have been made; and moving the paper loaded in the second loading portion to the first loading portion when the paper is judged to be loaded in the second loading portion. Thereafter, the first loading part may be performed in a step of raising from the first position to the second position.

After moving the paper loaded in the second loading part to the first loading part, the step of raising the first loading part from the first position to the second position is whether the side guide part is in a position where the paper loaded in the second loading part can move. Determining the step, moving the paper of the second loading portion to the first loading portion, and raising the first loading portion from the first position to the second position.

The step of determining whether the side guide portion is in the position where the paper loaded in the second loading portion can move, the step of determining the separation width of the first and second side guide portion of the side guide portion by the width sensor; The method may be performed by determining whether to transfer the paper according to the separation width of the first and second side guides of the side guide part. Optionally, the step of determining whether the paper is to be transported is externally alarmed or displayed when it is determined that the separation width of the first and second side guides of the side guide portion smaller than the width of the paper loaded in the second loading portion. It may further comprise the step.

In addition, the paper feeding method of the image forming apparatus of the present invention comprises the steps of determining whether or not the paper of the first loading portion, and the paper of the first loading portion to inform the outside of the paper consumption or to remove the paper of the second loading portion in accordance with It may further comprise the step of supplying to the loading portion.

Informing the paper consumption to the outside or feeding the second stack of paper into the first stacking unit when the paper is simultaneously loaded in the first and second stacking units or when it is determined that there is no paper in the second stacking unit Alarming and / or displaying externally, lowering the first loading portion from the second position to the first position when it is determined that the paper is separately loaded in the first and second loading portions and there is paper in the second loading portion. Determining whether the side guide portion is in a position to move the paper loaded in the second loading portion, moving the paper in the second loading portion to the first loading portion, and the first loading portion from the first position to the second position. It may be carried out in the step of raising.

Hereinafter, a paper feeding apparatus and a paper feeding method of the image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

2 shows a paper feeder 100 of an image forming apparatus according to a preferred embodiment of the present invention applied to an image forming apparatus such as a printer, a copying machine, or the like.

The paper feeding device 100 of the present invention includes a paper feed cassette 112, a first lifting unit 174, a second lifting unit 183, a paper feeding unit 113, a paper conveying unit 214, a paper detecting unit 244. , And a control unit (not shown).

The paper cassette 112 is a drawer-shaped rectangle composed of a front wall 115, a rear wall 116, first and second side walls 118 and 119, and a bottom wall 120 (see FIGS. 4 and 5). It is composed. The front wall 115 is provided with a handle 116a for moving the paper feed cassette 112 in the directions of arrows A and B to be taken out from the main body 111 or inserted into the main body 111. In the first and second side walls 118, when the paper feed cassette 112 is taken out from the inside of the main body 111 by the handle 116a or inserted into the main body 111, it is connected to the frame 103 of the main body 111. Only the first slide grooves of the first and second slide grooves 116b; the first side walls 118 are shown, which are engaged with the first and second protrusion sliders (not shown) formed and guided along the first and second protrusion sliders. ) Is formed.

The paper feed cassette 112 includes a side guide part 150, a rear guide part 235, and first and second loading parts 160 and 169 for loading paper therein.

The side guide part 150 includes first and second side guides 151 and 154 for guiding and setting the width of the paper perpendicular to the paper feeding direction (arrow C direction), that is, both edges of the paper. And an interlocking operation unit 159 for operating the second side guides 151 and 154 in cooperation with each other.

The first and second side guides 151 and 154 are formed in a plate-shaped plate having a first and second side guide surfaces 151a and 154a, respectively, and have a first paper stack of the first loading part 160. Guide grooves (not shown) formed in the bottom plate 120 of the paper cassette 112 to move in the arrow directions A and B along the first and second guide holes 161a and 161b formed in the plate 161. It is installed in).

The first and second racks 152 having first and second rack gears 153 and 156 constituting the interlocking operation part 159 at one lower side of the first and second side guides 151 and 154, respectively. 155 is formed to face each other. The pinion 157 is engaged with the first and second rack gears 153 and 156 between the first and second rack gears 153 and 156 and rotates on the rotating shaft 158 fixed to the bottom plate 120. It can be installed.

Therefore, when the user guides and sets both edges of the paper, the first and second side guides 151 and 154 may be moved even if only one is moved without having to move both of them in the arrow directions A and B. The two side guides 151 and 154 may be approached or spaced apart from each other by the first and second racks 152 and 155 and the pinion 157 of the interlocking operation unit 159.

The rear guide part 235 is for guiding the vertical width of the paper parallel to the paper feeding direction, that is, the upstream end edge of the paper feeding direction, and has an I-shaped vertical plate shape having the end guide surface 236a. The rear guide 236 is included. First and second sliding parts that can move along the third and fourth guide holes 169a and 169b formed in the second paper loading plate 169 of the second loading part 168 on both lower portions of the rear guide 236. Blocks 237 and 238 are formed. The first and second sliding blocks 237 and 238 are moved along the first and second sliding rods 270 and 271 by the paper transfer unit 214 as described below. And 271, first and second sliding holes (not shown) for receiving 271.

Each of the first and second loading portions 160 and 168 may separately load paper (hereinafter referred to as 'separate loading') or may stack paper so as to cover the paper at the same time (hereinafter referred to as 'simultaneous loading'). And second paper stacking plates 161 and 169.

The first and second paper loading plates 161 and 169 are downstream of the paper feed direction in the paper feed cassette 112 so as to be horizontally elevated by the first and second lifting units 174 and 183, which will be described later. (Left side of FIG. 2) and upstream (right side of FIG. 2).

When the paper is separately loaded on the first and second paper loading plates 161 and 169, the paper to be used is immediately loaded on the first paper loading plate 161 and the extra paper is loaded on the second paper loading plate 169. Is loaded. Therefore, when the paper is consumed in the first paper stacking plate 161 during the printing operation of the image forming apparatus, it is loaded on the second paper stacking plate 169 without the troublesome work of additionally supplying paper to the paper cassette 112. The printed paper may be supplied to the first paper stacking plate 161 by the paper transfer unit 214 described later.

In an embodiment of the present invention, the first paper loading plate 161 has a width of about 305 mm and a vertical width of about 210 mm, and the second paper loading plate 169 has a width of about 305 mm and a height of about 235 mm. It is formed to have. Therefore, when the paper is separately loaded, for example, A4 size (210 X 297 mm) paper can be loaded in the transverse direction on each of the first and second paper loading plates 161 and 169, and when the paper is loaded at the same time. Examples include A4 size (210 x 297 mm) paper, Letter size (216 x 279 mm) paper, Legal size (216 x 356 mm) paper, B4 size (257 x 364 mm) paper, A3 size (297 x 420 mm) paper. Paper and a Ledger size (279 X 432 mm) paper may be loaded in the first and second paper stacking plates 161 and 169 in the longitudinal direction.

The first lifting unit 174 includes a first lifter 175 and first and second position sensors 130 (see FIG. 3A) and 263. The first lifter 175 raises or lowers the first paper loading plate 161, and includes a first driving motor 117, a first lifting plate 176, and a second lifting plate 179. The first driving motor 117 is installed in the frame 103 of the main body 111 of the image forming apparatus. The first lifting plate 176 includes a first power transmission shaft 177 having a triangular first male coupling 182 formed at one end thereof. The first male coupling 182 is connected to the first female coupling 123 formed on the first driving shaft 117a of the first driving motor 117. The second lifting plate 179 has a second power transmission shaft 180 having a second gear 181 formed at one end thereof. The second gear 181 meshes with the first gear 178 formed on the first power transmission shaft 177.

As shown in FIGS. 3A and 3B, the first position sensor 130 picks up the paper in contact with the pickup roller 114 when the first paper stacking plate 161 is raised to the pickup roller assembly 113a. It is to detect whether the position is located, and is composed of a first sensing member 135, and the first sensor unit 131.

The first sensing member 135 is composed of a protrusion formed to protrude from one end of the pickup roller assembly 113a. The first sensor unit 131 is installed on the frame 103 to face the first sensing member 135 so as to detect the operation of the first sensing member 135, and has a light emitting part and a light receiving part. The light emitting portion and the light receiving portion are preferably composed of a light emitting diode and a photo transistor, respectively. The first sensor unit 131 outputs a 'low' signal, that is, an 'off' signal when the pickup roller assembly 113a is raised so that the first sensing member 135 is in a blocking position between the light emitting unit and the light receiving unit. When the pickup roller assembly 113a is raised or lowered and the first sensing member 135 is in an open position away from the light emitting unit and the light receiving unit, a 'high' signal, that is, an 'on' signal is output.

The second position sensor 263 is for detecting the stop position of the first plate guide 163 when the first plate guide 163 is lowered, and the second sensing member 264 and the second sensor unit 265. It is provided.

As shown in FIGS. 4 and 5, the second sensing member 264 includes a protrusion formed on the lower surface of the first paper stacking plate 161. The second sensor unit 265 is installed on the bottom plate 120 of the paper cassette 112 so as to face the second sensing member 264 and has a light emitting unit and a light receiving unit. Like the first sensor unit 131, the light emitting unit and the light receiving unit are preferably composed of a light emitting diode and a photo transistor. The second sensor unit 265 is turned off when the first paper stacking plate 161 is lowered and the second operating member 264 is positioned at a blocking position between the light emitting unit and the light receiving unit of the second sensor unit 265. 'On' signal when the first paper stacking plate 161 is raised and the second operating member 264 is located in an open position away from the light emitting part and the light receiving part of the second sensor part 265. Occurs.

In addition, in order to smooth the lifting operation of the first paper loading plate 161 when the first paper loading plate 161 is elevated by the first lifting unit 174, the first paper loading plate 161 and the paper feed cassette. The first plate guide 163 may be installed between the front wall 115 and the rear wall 116 of the 112. The first plate guide 163 is provided with first and second rollers 164 (only the second rollers are shown) and first and second rollers 164 installed on both sides of the first paper stacking plate 161, respectively. The first and second guide grooves 166 and 167 are formed in the front wall 115 and the rear wall 116, respectively.

The second lifting unit 183 includes a second lifter 184 that lifts and lowers the second paper loading plate 169 of the second loading unit 168. The second lifter 184 includes a second driving motor 200, a third lifting plate 185, and a fourth lifting plate 195.

The second driving motor 200 is installed in the frame 103 of the main body 111.

The third lifting plate 185 includes a third power transmission shaft 186 provided with a third gear 187 having a triangular second male coupling 188 formed at one end thereof. The second male coupling 188 is integral with the first driven pulley 209 connected to the drive gear 202 of the second driving shaft 201 of the second driving motor 200 by the first power transmission unit 199. It is connected to the second arm coupling 210 is formed. The first power transmission unit 199 includes a first power transmission gear 205 connected to the first gear 204 of the drive gear 202 and a pulley difference 206 connected to the first power transmission gear 205. A first driven pulley 207 and a first driven pulley 209 connected to the first driving pulley 207 through a power transmission belt 208.

The third power transmission shaft only when the second driving shaft 201 of the second driving motor 200, that is, the first driven pulley 209 and the third gear 187 rotate in one direction, for example, clockwise in FIG. 3. In order to transmit the rotational force of the first driven pulley 209 to 186, a first one-way power transmission unit 189 is installed between the third gear 187 and the third power transmission shaft 186.

As shown in FIGS. 6A and 6B, the first one-way power transmission unit 189 includes a first pivot boss 371, a first latch difference 373, a first height information 375, and a second latch difference. 376. The first pivot boss 371 is formed in the third gear 187. The first high information 375 and the second latch difference 376 are installed on one side of the cylindrical portion 342 formed at one end of the third power transmission shaft 186. The second latch vehicle 376 is supported by the fixing bracket 378 so as to be rotated at a predetermined angle to the bracket receiving groove 379 formed on one side of the cylindrical portion 342.

The first latch difference 373 and the second latch difference 376 are engaged with each other when the third gear 187 rotates in one direction, for example, in the clockwise direction of FIGS. 2 and 6A, from the first latch difference 373. The power is transmitted to the second latch car 376, and when the third gear 187 rotates in the other direction, for example, counterclockwise, they are staggered from each other, so that the first latch car 373 starts with the second latch car ( 376) to block power transmission.

Therefore, when the third gear 187 rotates in the clockwise direction of FIGS. 2 and 6A, the power of the second driving motor 200 is transferred to the third power by the first and second latch differences 373 and 376. Although transmitted to the shaft 186, when the third gear 187 rotates counterclockwise, the power of the second driving motor 200 is driven by the first and second latch differences 373 and 376 to the third power. It is not delivered to the delivery shaft 186.

The fourth lifting plate 195 includes a fourth power transmission shaft 196 having a fourth gear 197 engaged with the third gear 187 at one end thereof.

In order to transmit the rotational force of the fourth gear 197 to the fourth power transmission shaft 196 only when the fourth gear 197 rotates in the other direction, for example counterclockwise, the fourth gear 197 and the first Fourth power transmission shaft 196 is provided with a second one-way power transmission unit 198.

The second one-way power transmission unit 198, like the first one-way power transmission unit 189, the second rotation boss (not shown), the third latch (not shown), the second high information (not shown) ) And a fourth latch difference (not shown).

The second one-way power transmission unit 198 is configured to transmit the rotational force of the fourth gear 197 to the fourth power transmission shaft 196 only when the fourth gear 197 rotates in the other direction, ie counterclockwise. For the sake of brevity, the third and fourth latch differences are the same except that they are formed opposite to the first and second latch differences 373 and 376 of the second one-way power transmission unit 189.

Therefore, when the third gear 187 rotates in the clockwise direction and the fourth gear 197 engaged with the third gear 187 rotates in the counterclockwise direction, the fourth gear transfer shaft 196 has a fourth gear. When the rotational force of 197 is transmitted, and the third gear 187 rotates counterclockwise to rotate the fourth gear 197 clockwise, the fourth gear 197 is connected to the fourth power transmission shaft 196. ) Torque is not transmitted.

In order to smooth the lifting operation of the second paper loading plate 169 when the second paper loading plate 169 is lifted by the first lifting unit 183, the second paper loading plate 169 and the paper feed cassette 112 are used. The second plate guide 170 may be installed between the front wall 115 and the rear wall 116. The second plate guide 170 includes third and fourth rollers 171 (only the first roller is shown) and third and fourth rollers 171 which are respectively rotatably installed on both sides of the second paper stacking plate 169. The third and fourth guide grooves 173 and 175 are formed in the front wall 115 and the rear wall 116, respectively.

The paper feeding unit 113 includes a pickup roller assembly 113a and a pickup roller lifting unit 140.

The pick-up roller assembly 113a uses paper loaded on the first paper loading plate 161 when the first paper loading plate 161 of the first loading unit 160 is lifted by the first lifting unit 174. And a pickup roller 114 for picking up and feeding sheets one by one.

As shown in FIGS. 3A and 3B, the pickup roller lifting unit 140 has a pickup roller 114 of the pickup roller assembly 113a when the paper cassette 112 is inserted into the main body 111 in the arrow direction A. As shown in FIG. ) Is lowered toward the paper feed cassette 112 and when the paper feed cassette 112 is removed from the main body 111, the pickup roller 114 of the pickup roller assembly 113a is spaced apart from the paper feed cassette 112. 141, a compression spring 145, and a tension spring 144.

The lifting guide 141 is installed to move by the paper feed cassette 112 in the main body 111 and has a guide surface 143 for guiding the pickup roller assembly 113a to move up and down. The compression spring 145 is installed between the auxiliary frame 111a and the pickup roller assembly 113a so that the pickup roller assembly 113a contacts the guide surface 143 of the lifting guide 141. Press elastically. The tension spring 144 is installed on the lifting guide 141 and the auxiliary frame 111a so that the lifting guide 141 is raised to raise the pickup roller assembly 113a when the paper cassette 112 is removed.

The pickup roller lifting unit 140 is installed with respect to the main body 111 as described above, and is configured with respect to the pick up roller assembly 113a instead of being configured to lift the pickup roller assembly 113a by the paper cassette 112. It may also be of a known structure configured to lift the pickup roller assembly 113a by the paper feed cassette 112.

The paper conveying unit 214 is for conveying the paper loaded on the second paper stacking plate 169 to the first paper stacking plate 161 and pushes the paper toward the paper guide surface 236a of the rear guide 236. Consists of a conveying member 215 for moving to a position to be loaded on the paper loading first plate 161, and a third position sensor 266 for detecting the position of the rear guide 236 conveyed by the conveying member 215 do.

The conveying member 215 includes a fifth power transmission shaft 216, a linear motion converting part 220, and a second guide part 269.

The fifth power transmission shaft 216 is rotatably supported by the first and second support brackets 225 and 227, and has a sixth gear having a third male coupling 217 having a triangular shape at one end thereof. 218). The third male coupling 217 is connected to the third female coupling 212. The third arm coupling 212 is connected to the second gear 203 of the drive gear 202 formed on the second driving shaft 201 of the second driving motor 200 through the second power transmission unit 211. . The second power transmission part 211 includes a second power transmission gear 211a connected between the second gear 203 of the drive gear 202 and the external gear 212a of the third arm coupling 212. .

The linear motion conversion unit 220 converts the rotational force of the fifth power transmission shaft 216 into linear motion so as to reciprocate the rear guide 236 in the paper feeding direction (arrows C and D in FIG. 2). The first and second gears 239 and 242, the third and fourth driving pulleys 221 and 222, and the third and fourth driven pulleys 223 and 224 to be delivered to the rear guide 236. And first and second timing belts 229 and 230. The first and second gears 239 and 242 are formed in a U shape to receive and engage the first and second timing belts 229 and 230, and the first and second sliding blocks of the rear guide 236 ( 237 and 238, respectively. The third and fourth driving pulleys 221 and 222 are formed at predetermined intervals on the fifth power transmission shaft 216. The third and fourth driven pulleys 223 and 224 are formed of the paper cassette 112. Near the one side wall 118, the paper cassette 112 is supported on the bottom plate 120 so as to be rotatable to the fixing brackets 223 and 224. The first and second timing belts 229 and 230 are connected between the second and third driving pulleys 221 and 222 and the second and third driven pulleys 223 and 224, respectively, and have first and second timing belts 229 and 230 respectively. First and second corresponding gears (not shown) engaged with the second gear parts 239 and 242 and the third and fourth driven pulleys 221 and 222 and the third and fourth driven pulleys 223 and 224. It is provided.

 The second guide part 269 is for guiding the movement of the rear guide 236, and the first and second sliding rods 270 and 271 for guiding the movement of the first and second sliding blocks 237 and 238. It consists of. The first and second sliding rods 270 and 271 are fixed to a pair of third and fourth support brackets 272 and 273 and 274 and 275 at both ends, respectively. The first and second sliding rods 270 and 271 are inserted into the first and second sliding holes of the first and second sliding blocks 237 and 238, respectively, and thus the first and second sliding blocks 237 and 238. Guide your move.

The second drive shaft 201 of the second drive motor 200, that is, the third arm coupling 212 rotates in the other direction, for example, counterclockwise in FIG. 2, to the fifth power transmission shaft 216. In order to transmit the rotational force of the sixth gear 218, a third one-way power transmission part 219 is installed between the sixth gear 218 and the fifth power transmission shaft 216.

The third one-way power transmission unit 219 is similar to the second one-way power transmission unit 198, the third rotation boss (not shown), the fifth latch (not shown), the third high information (not shown) ) And a sixth latch wheel (not shown).

The third one-way power transmission unit 219 is configured to transmit the rotational force of the sixth gear 218 to the fifth power transmission shaft 216 only when the sixth gear 218 rotates in the other direction, ie counterclockwise. For this purpose, the second one-way power transmission unit 198 is formed substantially the same.

The third position sensor 266 is a third sensing member 268 formed under the protruding member 240 protruding from the first sliding block 237 of the rear guide 236 toward the rear wall 116, and the first sensing member 268. And a third sensor part 267 installed on the bottom plate 120 near the boundary of the second paper loading plates 161 and 169 and installed on the movement path of the third sensing member 268.

The third sensing member 268 is composed of a protrusion formed protruding from the lower portion of the protruding member 240. The third sensor unit 267 has a light emitting unit and a light receiving unit installed on the bottom plate 120 to face the third sensing member 268 to detect the operation of the third sensing member 268. The third sensor unit 267 outputs an 'off' signal when the third sensing member 268 is in a blocking position between the light emitting unit and the light receiving unit, and is turned on when the third sensing member 268 is in an open position away from the light emitting unit and the light receiving unit. Output the signal.

The paper detection unit 244 determines whether paper is loaded on each of the first and second paper loading plates 161 and 169, and whether the paper is loaded on the first and second paper loading plates 161 and 169 at the same time. By detecting the presence or absence, the width detection sensor 245, the vertical width detection sensor 249, the first loading sheet paper sensor 253, and the second loading sheet paper sensor 258.

The width detecting sensor 245 detects the width of the loaded paper, that is, the paper width in the vertical direction in the feeding direction. The width detecting sensor 245 has a protrusion formed on the bottom of the first rack 152 of the first side guide 151. The first operating member 246 and the first switch 247 formed in the movement path of the first operating member 246 on the bottom plate 120 of the paper feed cassette 112. The first switch 247 includes a plurality of first switching terminals 248 arranged to be switched by the first operating member 246 according to the movement of the first rack 152 of the first side guide 151. . In the embodiment of the present invention, the plurality of first switching terminals 248 is composed of five switching terminals to sense the widths of various sheets, for example, 210 mm, 216 mm, 257 mm, 280 mm, and 297 mm.

The vertical width sensor 249 detects the vertical width of the loaded paper, that is, the paper width parallel to the paper feeding direction, and includes a second protrusion having a protrusion formed at the lower end of the protruding member 240 of the rear guide 236. The operation member 250 and the second plate 251 formed in the movement path of the second operation member 250 on the bottom plate 120 of the paper feed cassette 112. The second switch 251 includes a plurality of second switching terminals 252 arranged to be switched by the second operating member 250 according to the movement of the protruding member 240 of the rear guide 236. In the embodiment of the present invention, the plurality of second switching terminals 252 are configured with four switching terminals to detect the vertical widths of various sheets, for example, 279 mm, 297 mm, 356 mm, and 364 mm.

The first loading unit paper detection sensor 253 detects whether the first paper loading plate 161 is loaded with paper, and includes a first sensing hole 257, a fourth sensing member 255, and a fourth sensor unit ( 254).

As shown in FIGS. 7A and 7B, the first sensing hole 257 is formed in the first paper loading plate 161. The fourth sensing member 255 is installed in the frame 103 of the main body 111 and has a first end 330 that is accommodated in or blocked from the first sensing hole 257 by its own weight depending on whether paper is loaded. do. The fourth sensor unit 254 has a light emitting unit and a light receiving unit provided to face the second end 336 of the fourth sensing member 255 to detect the operation of the fourth sensing member 255. The first and second ends 330 and 336 of the fourth sensing member 255 are supported by the support rod 332 to be rotatable to the frame 103.

Therefore, as illustrated in FIG. 7B, when the paper P is loaded on the first paper loading plate 161 at the position where the first paper loading plate 161 is raised, the fourth sensing member 255 may be formed. The first end 330 is lifted upward by the paper P, so that the second end 336 of the fourth sensing member 255 is blocked between the light emitting part and the light receiving part of the fourth sensor part 254. It is located in the open position away from the position. As a result, the fourth sensor unit 254 outputs an 'on' signal. On the contrary, as shown in FIG. 7A, when the paper P is not loaded on the first paper stacking plate 161 in the state where the first paper stacking plate 161 is raised, the fourth sensing member 255 may be formed. The first end 330 protrudes downward through the first sensing hole 257 of the first paper loading plate 161 due to its own weight, so that the second end 336 of the fourth sensing member 255 is It moves to a blocking position between the light emitting part and the light receiving part of the fourth sensor part 254. As a result, the fourth sensor unit 254 outputs an 'off' signal.

The second loading unit paper detection sensor 258 detects whether the first paper loading plate 169 is loaded with paper and at the same time, the vertical width of the paper that the height detection sensor 249 does not detect, such as 432 mm. Detecting the paper P of the Ledger size having a vertical width, and comprises a second sensing hole 260, a fifth sensing member 334, and a fifth sensor unit 331.

The second sensing hole 260 is formed in the second paper loading plate 169 close to the first side wall 118. The fifth sensing member 334 is elastically supported by the torsion spring 338 on the fixing bracket 139 'of the bottom plate 120 and is lowered through the second sensing hole 260 by the paper P. And a first end 259 that descends or protrudes upward. The fifth sensor part 331 has a light emitting part and a light receiving part provided to face the second end 335 of the fifth sensing member 334 so as to detect the operation of the fifth sensing member 334.

Therefore, as shown in FIG. 8B, when the paper P is loaded on the second paper stacking plate 169, the first end 259 of the fifth sensing member 334 is in contact with the weight of the paper P. FIG. The second end 335 is pressed down through the second sensing hole 260, and as a result, the second end 335 is disposed between the light emitting part and the light receiving part at a blocking position blocking the light emitting part and the light receiving part of the fifth sensor part 331. Moving to the open position to open, the fifth sensor unit 331 generates an 'on' signal.

On the contrary, as shown in FIG. 8A, when the paper P is removed or completely consumed from the second paper stacking plate 169, the first end 259 of the fifth sensing member 334 is torsion spring 338. By the elastic force of the protruding upward through the inner second sensing hole 260, as a result, the second end 335 is returned to the blocking position from the open position, the fifth sensor unit 331 is the 'off' signal Occurs.

Optionally, the paper detecting unit 244, in conjunction with the second loading paper detecting sensor 258, measures the vertical width of the paper, for example, 420 mm and 432 mm, which cannot be detected by the vertical width sensor 249. The sensor may further include a separate sensor 280.

The separate sensor 280 includes a rotating member 281, a sixth sensing member 282, and a sixth sensor unit 283. As shown in FIGS. 9A and 9B, the rotating member 281 has a second paper loading plate 169 so that a part thereof protrudes into the paper loading space of the second paper loading plate 169 of the second loading portion 168. The hinge shaft 286 formed on the paper guide wall 116a of the rear wall 116 is pivotally installed near the opening 169c of the back side wall. The sixth sensing member 282 is configured of a protrusion protruding from the inner surface of the rotating member 281. The sixth sensor unit 283 has a light emitting unit and a light receiving unit provided on the paper guide wall 116a to face the sixth sensing member 282 so as to detect the operation of the sixth sensing member 282.

Therefore, as shown in Fig. 9B, when a large sheet of paper such as A3 and Ledger size paper is loaded on the first and second sheet paper plates 161, 169, the rotating member 281 is placed on one side edge of the sheet of paper. And pivoted clockwise about the hinge axis 286, whereby the sixth sensing member 282 is opened at the blocking position between the light emitting portion and the light receiving portion of the sixth sensor portion 283. Is moved to. As a result, the sixth sensor unit 283 generates an 'on' signal.

Conversely, as shown in Fig. 9A, when paper smaller than A3 and Ledger size paper is loaded on the first and second paper stacking plates 161 and 169, the rotating member 281 is the solenoid 285 described later. It is pushed by the compression spring 320 of the pivot about the hinge axis 286 counterclockwise, whereby the sixth sensing member 282 is moved from the open position to the blocking position. As a result, the sixth sensor unit 283 generates an 'off' signal.

When the paper transfer unit 214 transfers the paper loaded on the second paper loading plate 169 to the first paper loading plate 161, the paper is prevented from being caught by the rotating member 281 of the separate sensor 280. To this end, the separate sensor 280 rotates the rotating member 281 so that the portion of the rotating member 281 protruding into the paper loading space of the second paper loading plate 169 retreats out of the paper loading space. The solenoid 285 may further include.

As shown in FIG. 9C, the solenoid 285 includes a plunger 318, a coil 319, a compression spring 320, and a case 317.

The plunger 318 is formed of a metal or magnet which can be operated by magnetic force, and has a straight hole and a fixing hole 318b to which the connecting pin 336 inserted into the connecting hole 284 of the rotating member 281 is fixed. Grooves 318a are formed.

The coil 319 generates a magnetic force when a current is applied, attracts the plunger 318 and moves it in the arrow direction G of FIG. 9C. The coil 319 is supported by the yoke 321.

The compression spring 320 is to move the plunger 318 upward in the direction of the arrow F of FIG. 9 when no current is applied to the coil 319 to return it to the original position. It is installed between the washer 318c and the top of the case 317.

Therefore, when the solenoid 285 is turned on, that is, when a current is applied to the coil 319, the plunger 318 moves in the direction of the arrow G and through the connecting pin 336 inserted into the connecting hole 284. The rotating member 281 is pivoted about the hinge axis 286 in the clockwise direction of FIG. 9A, and as a result, as shown in FIG. 9B, protrudes into the paper loading space of the second paper loading plate 169. The portion of the rotating member 281 is retracted out of the paper loading space.

In addition, when the solenoid 285 is turned off, that is, when no current is applied to the coil 319, the plunger 318 moves in the arrow direction F by the elastic force of the compression spring 320 to connect the connection hole 284. The rotating member 281 is rotated in the counterclockwise direction of FIG. 9B about the hinge shaft 286 through a connecting pin 336 inserted into the rotating member 281, as a result, as shown in Figure 9a, the rotating member 281 Is partially projected into the paper loading space of the second paper loading plate 169.

The control unit controls each component of the image forming apparatus, and is composed of a microchip such as a microprocessor embedded in a circuit board (not shown). The control unit is connected to the first and second drive motors 117 and 200, the first, second and third position sensors 130, 263 and 266 by a connecting means such as a connecting line (not shown) and the width detecting sensor. 245, the vertical width sensor 249, the first loading sheet paper sensor 253, the second loading sheet paper sensor 258, the separate sensor 280, and the like are electrically connected to each other.

In the control unit, after the paper feed cassette 112 is inserted into the main body 111 and mounted thereon, the paper is first loaded according to the signals output from the sensors 245, 249, 258, and 280 of the paper detection unit 244. And determining whether the second paper stacking plates 161 and 169 are loaded at the same time, and raising the first and second paper stacking plates 161 and 169 together or the first paper stacking plate according to the presence of the simultaneous stacking. The first and / or second elevating unit 174, and / or 183 is controlled to raise only 161.

That is, the control unit is configured to transfer the paper to the first and second paper stack plates 161 and 169 from the signals output from the sensors 245, 249, 258 and 280 of the paper detection unit 244, that is, the 'on' signal. It is judged whether or not it is loaded at the same time as Table 1 below.

TABLE 1

Width sensor 210 mm O 216 mm O O 257 mm O 280 mm 0 297 mm O 0 0 Vertical width sensor 279 mm O 297 mm 0 356 mm O 364 mm O Second loading paper sensor O O 0 Separation Sensor O O O 0 Judgment result Simultaneous loading (A4 size) Simultaneous loading (letter size) Simultaneous loading (Legal size) Simultaneous loading (B4 size) Simultaneous loading (A3 size) Simultaneous loading (Ledger size) Separately loaded (A4 size, 1st paper loading plate only) Separately loaded (A4 size, 2nd paper loading plate only) Separately loaded (A4 size, loaded on both first and second paper loading plates) Out of paper or error

* O means 'on' signal.

As a result, as shown in Fig. 4, when the paper P is loaded at the same time, the control unit raises the first and second paper loading plates 161 and 169 together to pick up the paper of the pickup roller assembly 113a. The first and second lifting units 174, 183 are controlled to be in the pick-up position in contact with the roller 114.

As a result of the decision, as shown in FIG. 5, when the paper is separately loaded, the control unit determines whether the paper P1 is loaded on the first paper loading plate 161 as shown in Table 1 above. If it is judged by the signal output from the paper and it is determined that there is paper P1, for example, A4 size paper, on the first paper loading plate 161, the first paper loading plate 161 is raised to raise the paper P1. Control the first elevating unit 174 to position "

At this time, if it is determined by the signal from the width detecting sensor 245 that the paper P1, that is, A4 size paper, is present in the first paper loading plate 161, the control unit is as shown in Table 1 above. It is determined whether paper P1, for example, A4 size paper, is loaded on the second paper loading plate 169 by the signals output from the second loading unit paper detection sensor 258 and the separate sensor 280. If it is determined that the paper P1 is loaded on the second paper loading plate 169, the second lifting unit 183 is controlled to raise the second paper loading plate 169.

In addition, it is determined that there is no A4 size paper in the first paper stacking plate 161 by the signal from the width detecting sensor 245, and the second paper distribution sensor 258 and the separate sensor 280 If it is determined by the output signal that there is A4 size paper in the second paper stacking plate 169, the control unit selects the paper P1 loaded on the second paper stacking plate 169 to the first paper stacking plate 161. Control the paper conveying unit 214 to convey to; If it is determined that the paper P1 is not loaded in both the first and second paper stacking plates 161 and 169, a paper out or an error is transmitted to the outside through a speaker (not shown) installed in the main body 111. Alert or display out of paper or error via a liquid crystal display (not shown) on the control panel (not shown).

In addition, the control unit determines whether or not paper is loaded in the first paper loading plate 161 by a signal output from the first loading unit paper detection sensor 253 when the paper is fed by the pickup roller 114, If it is determined that paper is consumed in the first paper loading plate 161, the paper consumption is determined according to whether there is simultaneous loading of paper and whether there is paper separately loaded on the second paper loading plate 169. Alternatively, the paper conveying unit 214 may be controlled to alert or display to the outside through the liquid crystal display or to convey the paper P1 loaded on the second paper loading plate 169 to the first paper loading plate 161. have.

That is, if it is determined that the paper is consumed on the first paper loading plate 161 and then the paper is determined to be loaded on the first and second paper loading plates 161 and 169 at the same time, the control unit has no paper through the speaker. Alarm on the outside or paperless display on the liquid crystal display.

In this case, when it is determined that the paper is separately loaded on the first and second paper loading plates 161 and 169, the control unit controls the first lifting unit 174 to open the first paper loading plate 161. It is lowered, and the presence or absence of the paper of the second paper loading plate 169 is determined by the signals from the second loading unit paper detection sensor 258 and the separate sensor 280, and as a result of determination, the paper P1, for example, When it is determined that A4 size paper is loaded, the positions of the first and second side guides 151 and 154 of the side guide part 150 are determined based on a signal from the width detecting sensor 245. The first and second side guides 151 and 154 of the first loading unit 160 determine whether the sheet of paper P1 loaded on the second paper loading plate 169 is in a position where the first loading unit 160 can move. If it is determined that the first and second side guides 151 and 154 are in a position where they do not interfere with the conveyance of the paper P1, the control unit controls the paper conveying unit 214 to control the second paper loading plate. The paper P1 loaded in 169 is transferred to the first paper stacking plate 161. After the paper P1 is transferred to the first paper stacking plate 161, the control unit raises the first paper stacking plate 161 to position the paper P1 at the pick-up position. To control. Thereafter, the control unit controls the pickup roller drive motor (not shown) which drives the pickup roller 114 to pick up the paper P1 through the pickup roller 114 and feed the sheet P1 into the main body 111 one by one.

As described above, the sheet feeding apparatus 100 of the image forming apparatus according to the present invention may include a sheet detecting unit 244 capable of sensing various sheets and first and second loading portions 161 according to the size of the detected sheets. And 164, the first and second lifting units (174, 183) for lifting up and down at the same time, it is possible to simultaneously load a large sheet on the first and second paper loading plate (161, 169) In addition, small sheets of paper may be separately loaded on the first and second paper stacking plates 161 and 169.

In addition, the paper feeder 100 of the image forming apparatus according to the present invention is provided with an interlocking operation unit 159 that can operate in conjunction with the first and second side guides 151, 154 of the side guide portion 150. Therefore, it provides an effect that can easily set the paper.

In addition, the sheet feeding apparatus 100 of the image forming apparatus according to the present invention includes first and second paper loading plates 161 and 169 and second paper loading plates 169 capable of simultaneously and separately loading paper. Since the paper conveying unit 214 can automatically transfer the loaded paper to the first paper stacking plate 161, when the small paper such as A4 size paper is used, the paper is placed on the first paper stacking plate 161. When exhausted, the paper loaded in the second paper stacking plate 169 is transferred to the first paper stacking plate 161 by the temporary paper transfer unit 214 without the troublesome work of additionally feeding the paper into the paper cassette 112. Can supply

In the above, the paper feeding device 100 of the image forming apparatus according to the present invention has been illustrated and described that the first and second paper loading plates 169 are configured to allow the A4 size paper to be redundantly loaded. It is not limited to. That is, the present invention may be configured such that the first and second paper-loading plates 169 can additionally load other paper, for example, B5 size paper, instead of A4 size paper.

The operation of the paper feeder 100 of the image forming apparatus according to the present invention configured as described above will be described with reference to FIGS. 2 to 10.

   First, after the paper required for the paper cassette 112 is loaded, the first and second side guides 151 and 154 and the rear guide 236 are moved to guide and set both side edges and end edges of the loaded paper. .

      Subsequently, the paper feed cassette 112 is pushed in the arrow direction A by the handle 116a and inserted into the main body 111 (S1). At this time, the first and second slide grooves 116b of the paper cassette 112 are moved while being guided along the first and second protrusion sliders of the main body 111, and the protruding jaw 142 of the lifting guide 141 is moved. As shown in FIG. 3A, the tip of the paper feed cassette 112 is pushed in the arrow direction A. As shown in FIG. As a result, as shown in FIG. 3B, the pickup roller assembly 113a located above the paper feed cassette 112 has a guide surface 143 of the lifting guide 141 around the rotation shaft by the compression spring 145. And descends while rotating in the direction of the arrow (E).

After that, when the paper feed cassette 112 is completely inserted into the main body 111, the pickup roller assembly 113a is in a state where the pickup roller 114 is positioned above the leading end of the paper in the paper cassette 112, The first, second, and third male couplings 182, 288, and 217 installed on the first, third, and fifth power transmission shafts 177, 186, and 216 to protrude outward from the cassette 112 may include the first, third, and fifth male couplings 182, 288, and 217. Meshes with the second and third arm couplings 123, 210, and 212.

In this state, the control unit is output from the width detecting sensor 245, the vertical paper detecting sensor 245, the second loading part paper detecting sensor 258 and the separate sensor 280 of the paper detecting unit 244. According to the signal, it is determined whether paper is loaded on the first and second paper stacking plates 161 and 168 simultaneously (S2).

As a result of the determination in step S2, for example, A3 size paper (as illustrated in Table 1 above) by the 'on' signal from the width paper detection sensor 245 and the separate sensor 280 of the paper detection unit 244 ( If P) is determined to be simultaneously loaded, the control unit first and second lifting units 174 and 183 to raise together the first and second paper loading plates 161 and 169 as shown in FIG. The first and second driving motors 117 and 200 are controlled to be driven in one direction, ie counterclockwise and clockwise, respectively. At this time, the power of the second driving motor 200 is the third and fourth power transmission shafts of the third and fourth lifting plates (186, 195) by the first and second one-way power transmission units (189, 198). 186 and 196, but not to the fifth power transmission shaft 216 by the third one-way power transmission 219. As a result, the first and second paper stacking plates 161, 169 are raised and moved to the pick-up position where the paper P is brought into contact with the pick-up roller 114 of the pick-up roller assembly 113a.

As the first and second paper loading plates 161 and 169 are raised in this manner, the paper P loaded on the first paper loading plate 161 is brought into contact with the pickup roller 114 to the compression spring 145. The pickup roller 114 is pushed up against it, whereby the pickup roller assembly 113a rotates upward along the rotation shaft.

When the pick-up roller assembly 113a is raised upward and the paper P is located at the pick-up position in contact with the pick-up roller 114 at a constant pressure, the first sensing member 134 formed at one end of the pick-up roller assembly 113a ) Is positioned at a blocking position between the light emitting unit and the light receiving unit of the first sensor unit 131, and thus the first sensor unit 131 generates an 'off' signal.

As the fifth sensor unit 131 generates an 'off' signal, the control unit stops the first and second driving motors 117 and 200 (S3).

On the other hand, as a result of the determination in step S2, the output from the width detection sensor 245, the vertical paper detection sensor 245, the second loading unit paper detection sensor 258 and the separate sensor 280 of the paper detection unit 244 When it is determined that the paper P is separately loaded by the received signal, the control unit determines whether the paper P1 is loaded on the first paper loading plate 161 (S4).

In step S4, for example, the width paper detection sensor 245 of the paper detection unit 244, or the width paper detection sensor 245, the second loading unit paper detection sensor 258 and the separate sensor 280 If it is determined by the ON 'signal that A4 size paper is separately loaded on the first paper loading plate 161 or the first and second paper loading plates 161 and 169 as illustrated in Table 1 above, the control unit Controls only the first driving motor 117 of the first lifting unit 174 in the counterclockwise direction so as to raise only the first paper loading plate 169. As a result, as shown in Fig. 5, the first paper loading plate 161 is raised in the same manner as in step S3 to pick up the paper P1 in contact with the pickup roller 114 of the pickup roller assembly 113a. It is moved to the position (S5).

Further, as a result of the determination in step S4, the width paper detection sensor 245 or the width paper detection sensor 245, the second loading unit paper detection sensor 258, and the separate sensor 280 to the 'off' signal If it is determined that the paper P1 is not loaded on the first paper loading plate 161, the control unit determines whether the paper P1 is loaded on the second paper loading plate 169 (S6).

In step S6, when it is determined that no A4 size paper is loaded in the second paper stacking plate 169 because no 'ON' signal is output from any of the sensors as illustrated in Table 1 above, the control unit determines the first and It is determined that no paper is loaded or an error anywhere in the second paper loading plates 161 and 169, and an alarm for a paper out or an error through a speaker, a paper out or an error message is displayed through a liquid crystal display, and the user displays it. Wait for processing (S7).

On the other hand, as a result of the determination in step S6, for example, by the 'on' signal output from the second loading unit paper sensor 258 and the separate sensor 280 as shown in Table 1 above, the second paper loading plate 169 When it is determined that A4 size paper is loaded in the control unit, the control unit transfers the paper by the first and second side guides 151 and 154 of the side guide part 150 by a signal output from the width detecting sensor 245. It is determined whether or not the position is suitably positioned in the position, that is, the separation widths of the first and second side guides 151 and 154 are wider than the width of the A4-size paper (that is, 297 mm) (S8).

In step S8, when it is determined that the first and second side guides 151, 154 of the side guide part 150 are properly positioned for paper feeding, the control unit loads the paper loaded on the second paper stacking plate 169. In order to transfer P1 to the first paper stacking plate 161, the second driving motor 200 is controlled to be driven in another direction, that is, counterclockwise. At this time, the power of the second driving motor 200 is transmitted to the fifth power transmission shaft 216 by the third one-way power transmission unit 219, but to the first and second one-way power transmission units (189, 198). It is not transmitted to the third and fourth power transmission shafts 186 and 196 of the third and fourth lifting plates 185 and 195. As a result, the paper guide surface 236a of the rear guide 236 pushes the paper P1 loaded on the second paper loading plate 169 to transfer it to the first paper loading plate 161.

Thereafter, when the paper P1 is completely transferred to the first paper stacking plate 161, the third sensing member 268 of the third position sensor 266 may be disposed between the light emitting portion and the light receiving portion of the third sensor portion 267. In the blocking position, the third sensor unit 267 generates an 'off' signal.

As the third sensor unit 267 generates an 'off' signal, the control unit stops driving of the second driving motor 200 (S10).

In addition, in step S8, if it is determined that the first and second side guides 151 and 154 of the side guide part 150 are not properly positioned for conveying the paper, the control unit first and second side guides 151 154 alerts that the improperly positioned is through the speaker or is displayed via the liquid crystal display and waits for the user to process it (S9).

In this way, in steps S5 and S10, the first and second paper loading plates 161 and 169 or the first paper loading plate 161 are raised to pick up the paper P or P1 of the pickup roller assembly 113a. When located at the pick-up position in contact with the pick-up roller 114, the control unit drives the pick-up roller 114 by a pick-up roller drive motor connected to the pick-up roller 114 via a gear train (not shown). 114 and the paper, that is, the paper located at the top of the paper P or P1 loaded on the first paper stacking plate 112 are sequentially supplied one by one into the main body 111 (S11).

As the paper P or P1 is supplied into the main body 111 as described above, when all of the paper P or P1 loaded on the first paper stacking plate 112 is exhausted, as shown in FIG. 7A. The fourth sensing member 255 of the first paper loading sensor 253 has a first end 330 inserted into the first sensing hole 257 of the first paper loading plate 161 by its own weight. Accordingly, the second end portion 336 moves to a blocking position between the light emitting portion and the light receiving portion of the fourth sensor portion 254. As a result, the fourth sensor unit 254 generates an 'off' signal.

As the fourth sensor unit 254 generates an 'off' signal, the control unit determines that there is no paper P or P1 in the first paper stacking plate 161 (S12).

Subsequently, the control unit determines whether the paper P or P1 is loaded at the same time based on the result determined in step S2 (S13).

At this time, if the paper P has been loaded at the same time, the control unit moves to step 20 to alert the paper out through the speaker and / or to display the paper out message through the liquid crystal display and wait for the user to take action.

However, if the paper P1 is not loaded at the same time, the control unit determines whether the paper P is on the second paper loading plate 169 in the same manner as in step 6 (S14).

That is, the control unit determines whether there is an 'on' signal output from the second loading unit paper sensor 258 and the separate sensor 28, and according to the presence or absence of the 'on' signal, the second paper loading plate 169. The presence or absence of the paper P1.

If it is determined that the paper P1 is not loaded on the second paper stacking plate 169, the control unit performs the operation of step S20.

In addition, when it is determined that the paper P1 is loaded on the second paper loading plate 169, the control unit may move the first driving motor (1) of the first lifting unit 174 to lower the first paper loading plate 169. 117 is controlled to drive in the other direction, that is, clockwise. As a result, the first paper loading plate 161 is lowered (S15).

Thereafter, when the first paper stacking plate 161 is completely lowered, the second sensing member 264 of the second position sensor 263 is positioned at a blocking position between the light emitting portion and the light receiving portion of the second sensor portion 265. Accordingly, the second sensor unit 265 generates an 'off' signal.

As the second sensor unit 265 generates an 'off' signal, the control unit is adapted to transfer the first and second side guides 151 and 154 of the side guide part 150 in the same manner as in step S8. It is determined whether to position (S16).

  At this time, the control unit performs the operation of step S9 if it is determined that the first and second side guides 151 and 154 are not positioned for paper feeding, and if it is determined that the first and second side guides 151 and 154 are suitable for paper feeding, step S10. In the same manner as described above, the paper transfer unit 214 is controlled to transfer the paper P1 from the second paper loading plate 169 to the first paper loading plate 161 (S17).

Thereafter, the control unit drives the pickup roller 114 by the pickup roller driving motor in a manner similar to that of step S11, and supplies the sheets P1 one by one into the main body 111 one by one (S18).

As the paper P1 is supplied into the main body 111, when all of the paper P1 loaded on the first paper loading plate 112 is exhausted, as in step S12, the first paper loading sensor 253 The fourth sensor unit 254 generates an 'off' signal.

As the fourth sensor unit 254 generates an 'off' signal, the control unit determines that there is no paper in the first paper stacking plate 161 (S19), and alarms that there is no paper through the speaker and / or The paperless message is displayed through the liquid crystal display, and the user waits to take an action (S20).

On the other hand, as the speaker generates an alarm in steps S7, S9, and S20 and / or a message is displayed on the liquid crystal display, when the user pulls the paper cassette 112 with the handle 116a, the paper cassette 112 As shown in FIG. 2, the first and second slot grooves 116b are guided out along the first and second protrusion sliders of the main body 111.

In this case, the first, second, and third male couplings 182, 288, and 217 installed on the first, third, and fifth power transmission shafts 177, 186, and 216 may include the first, second, and third arms. It is released from the couplings 123, 210, 212. As a result, the gear forces of the first and second drive motors 117 and 200 acting on the first, second and third male couplings 182, 288 and 217 are released, and the first and second lifting plates 161 and 169 are lowered by weight and positioned in a horizontal position.

In addition, the elevating guide 141 is pulled by the elastic force of the compression spring 144, accordingly, the pickup roller assembly 113a is a guide surface 143 of the elevating guide 141, as shown in Figure 3b Rising along, it returns to the position shown in FIG. 3A.

Thereafter, the paper feed cassette 112 is loaded with the paper P or P1 required by the user, and then repeats the operation after step S2.

As described above, the paper feeding device and the paper feeding method of the image forming apparatus according to the present invention simultaneously lift or separate the first and second loading portions according to the paper sensing unit capable of sensing various sheets and the size of the detected sheets. Since the first and second lifting units can be elevated, various sheets of paper, that is, large sheets of paper, can be loaded on the first and second sheets of paper simultaneously, and small sheets of paper can be loaded on the first and second sheets of paper. Provide a beneficial effect.

In addition, the paper feeder and the feeding method of the image forming apparatus according to the present invention has an interlocking operation portion that can operate in conjunction with the first and second side guides of the side guide portion, the effect of making the setting of the paper easier To provide.

In addition, the paper feeding apparatus and the paper feeding method of the image forming apparatus according to the present invention, the first and second paper loading plate that can simultaneously or separately load the paper, and the paper stacked on the second paper loading plate the first paper With a paper transfer unit that can automatically transfer to the loading plate, not only can you increase the paper load when you use small paper such as A4 size paper, but also when the paper is used up on the first paper loading plate It provides the effect of supplying the paper loaded on the second paper stacking plate to the first paper stacking plate by the paper transfer unit, without the troublesome work of supplying paper to the paper.

In the above, certain preferred embodiments of the present invention have been illustrated and described. However, the present invention is not limited to the above-described embodiments, and any person skilled in the art without departing from the gist of the present invention claimed in the claims may make various modifications and changes. Would be possible.

Claims (39)

A paper feed cassette having a side guide part for guiding and setting the width of the paper, a rear guide part for guiding and setting the vertical width of the paper, and first and second loading parts capable of simultaneously or separately loading the paper; A first elevating unit installed in the paper feed cassette and elevating the first loading unit; A second elevating unit installed in the paper feed cassette and elevating the second loading unit; A paper feeder provided with a pickup roller which picks up and feeds sheets of paper stacked in the first stacker one by one when the first stacker is raised; A paper conveying unit which is installed in the paper feed cassette and conveys the paper loaded in the second loading unit to the first loading unit; A paper detecting unit which detects whether paper is loaded on each of the first and second loading units and whether paper is loaded on the first and second loading units at the same time; And Controlling the first and second lifting portions so as to lift at least one of the first and second loading portions according to whether paper is simultaneously loaded in the first and second loading portions, and the first and second And a control unit for controlling the paper conveying unit to transfer the paper loaded in the second loading unit to the first loading unit according to whether paper is loaded on each stacking unit. Device. The method of claim 1, The control unit controls to raise and lower both the first loading portion and the second loading portion when paper is simultaneously loaded in the first and second loading portions, and the paper is separately loaded in the first and second loading portions. When the paper is loaded only in the second loading portion, and controls to transfer the paper loaded in the second loading portion to the first loading portion. A paper feeder of an image forming apparatus. According to claim 1, The side guide portion, First and second side guides for supporting and guiding both side edges of the paper in the first loading portion; And And an interlocking operation unit configured to operate the first and second side guides in association with each other. According to claim 3, The linkage operation unit, A first rack formed on the first side guide; A second rack formed on the second side guide; And And a pinion rotatably installed in the paper feed cassette between the first and second racks and engaged with the first and second racks. 2. The first and second paper stacks according to claim 1, wherein the first and second stacking portions are provided so as to be able to elevate to the first and second positions downstream and upstream of the paper feed direction, respectively, and to stack the paper. Paper feeder of the image forming apparatus, characterized in that it comprises a plate. The method of claim 1, wherein the first lifting unit, A first lifter for elevating the first loading portion to first and second positions; A first position sensor detecting a first position of the first loading part; And And a second position sensor for sensing a second position of the first loading portion. The method of claim 6, wherein the first lifter, A first driving motor; A first lifting plate having a first power transmission shaft having a first corresponding coupling connected to a first coupling formed at a first driving shaft of the first driving motor at one end thereof; And And a second lifting plate having a second power transmission shaft having a second gear engaged with the first gear formed on the first power transmission shaft. The method of claim 6, wherein the first position sensor, A first sensing member formed on the paper feeder; And And a first sensor unit provided to face the first sensing member so as to detect an operation of the first sensing member. The method of claim 6, wherein the second position sensor, A second sensing member formed on the first loading portion; And And a second sensor unit provided in the paper feed cassette so as to face the second sensing member so as to detect the operation of the second sensing member. The paper feeder of claim 6, wherein the first lifter further comprises a first plate guide for guiding movement of the first loading part. The method of claim 10, wherein the first plate guide, At least one pair of first and second rollers respectively installed on both sides of the first loading part in a feeding direction; And And at least one pair of first and second guide grooves respectively formed in the paper feed cassette so as to face the first and second rollers. The paper feeder of claim 1, wherein the second lifter includes a second lifter for lifting the second loading part to the first and second positions. The method of claim 12, wherein the second lifter, Second driving motor; A third lifting plate including a third power transmission shaft having a second corresponding coupling coupled to a second coupling coupled to the second driving shaft and the first power transmission unit of the second driving motor; And And a fourth lifting plate having a fourth power transmission shaft having a fourth gear engaged with the third gear installed on the third power transmission shaft. The method of claim 13, wherein the second lifter is provided between the third and fourth gears and the third and fourth power transmission shafts, respectively, the third and fourth gears only when the second drive motor rotates in one direction. And a first and a second one-way power transmission unit for transmitting the rotational force of the fourth gear to the third and fourth power transmission shafts, respectively. The paper feeder of claim 12, wherein the second lifter further comprises a second plate guide for guiding movement of the second loading part. The method of claim 15, wherein the second plate guide, At least one pair of third and fourth rollers respectively installed to be rotatable on both side surfaces of the second loading portion in the feeding direction; And And at least a pair of third and fourth guide grooves respectively formed in the paper feed cassette so as to face the third and fourth rollers. The method of claim 1, wherein the paper transfer unit, A conveying member for conveying the rear guide part so that the paper loaded in the second loading part is moved to a position where the paper is loaded in the first loading part; And And a third position sensor for sensing a position of the rear guide part carried by the conveying member. The method of claim 17, wherein the transfer member, A fifth power transmission shaft having a third corresponding coupling coupled to a third coupling connected to a second driving shaft of the second driving motor through a second power transmission unit at one end thereof; A linear motion converting unit converting the rotational force of the fifth power transmission shaft into a linear motion so as to reciprocate the rear guide part in a paper feeding direction and transferring the rear guide part to the rear guide part; And And a second guide part for guiding movement of the rear guide part. 19. The method of claim 18, wherein the transfer member is provided between the third coupling and the fifth power transmission shaft, the rotational force of the third coupling is only when the second drive motor rotates in the other direction And a third one-way power transmission unit configured to be transmitted to the fifth power transmission shaft. The method of claim 18, wherein the linear motion conversion unit, At least one drive pulley formed on the fifth power transmission shaft; At least one driven pulley installed in the paper feed cassette; And And a timing belt connecting the driving pulley and the driven pulley and having a corresponding tooth portion engaged with the tooth portion of the rear guide portion. The method of claim 17, wherein the third position sensor, A third sensing member formed on the rear guide portion; And And a third sensor unit provided in the paper feed cassette and installed to face the third sensing member so as to detect the operation of the third sensing member. The method of claim 1. The paper detection unit, A width detecting sensor for detecting widths of a plurality of sheets; A vertical width sensor for sensing vertical widths of the plurality of sheets; A first loading part paper sensor for detecting whether the first loading part is loaded or not; And And a second loading unit paper sensor for detecting whether the second loading unit is loaded with paper. The method of claim 22, The width detecting sensor includes a first switch having a first operating member formed under the side guide part, and a first switch having a plurality of switching terminals formed in a movement path of the first operating member in the paper feed cassette; The vertical width sensor comprises a second switch having a second operating member formed below the rear guide portion, and a second switch having a plurality of switching terminals formed in a movement path of the second operating member in the paper feed cassette; The first loading part paper sensor is formed in the first sensing hole formed in the first loading part, the frame of the main body, and the first end is accommodated in the first sensing hole or blocked by its own weight depending on whether the paper is loaded. A fourth sensing member having a fourth sensor portion provided opposite to a second end of the fourth sensing member to detect an operation of the fourth sensing member; The second loading unit paper sensor is formed in the second sensing hole formed in the second loading unit, the paper feed cassette, the first projecting out through the second sensing hole or lowered down by the weight of the paper And a fourth sensor unit provided opposite the second end of the fifth sensing member to detect the operation of the fifth sensing member. 23. The paper feeder of claim 22, wherein the paper detector further comprises a separate sensor configured to detect a vertical width of a sheet that the vertical width sensor cannot detect. The method of claim 24, wherein the separate sensor, A rotating member pivotally installed near the second loading portion of the paper feed cassette such that a portion thereof protrudes into the paper loading space of the second loading portion; A sixth sensing member protruding from the rotating member; And And a sixth sensor unit provided to face the sixth sensing member so as to detect the operation of the sixth sensing member of the rotating member. 26. The rotary member of claim 25, wherein the separator sensor is configured to protrude into the paper loading space of the second loading portion when the paper transfer portion transfers the paper loaded in the second loading portion to the first loading portion. And a solenoid which rotates the rotating member so that a portion moves out of the paper loading space of the second loading portion. Determining, by the control unit, whether or not the paper is loaded on the first and second loading portions at the same time; Raising, by the control unit, at least one of the first and second loading portions from the first position to the second position according to whether paper is simultaneously loaded on the first and second loading portions, and And controlling the paper feeding unit to pick up the sheets one by one and feed the sheets into the image forming apparatus. 28. The method of claim 27, wherein the step of determining whether paper is loaded simultaneously with the first and second loading portions, Determining whether the width sensor and the height sensor are 'on'; Determining that paper is simultaneously loaded in the first and second loading portions when it is determined that both the width sensor and the height sensor are 'on'; And Determining that the paper is separately loaded in the first and second loading parts when the width detecting sensor is 'on' and the height detecting sensor is 'off'. Feeding method of the forming apparatus. 28. The method of claim 27, wherein the step of determining whether paper is loaded simultaneously with the first and second loading portions, Determining whether the width sensor, the height sensor, the second paper sheet sensor, and the separate sensor are 'on'; When at least one of the vertical width sensor, the second loading part paper sensor, and the separate sensor and the width detection sensor are determined to be 'on', the paper is loaded on the first and second loading parts simultaneously. Judging by; And And determining that the paper is separately loaded in the first and second loading parts when the second loading part paper sensor, the separate sensor, the width sensor, or both are determined to be 'on'. And a feeding method of an image forming apparatus. 30. The method according to any one of claims 28 and 29, wherein the step of determining whether paper is loaded simultaneously with the first and second loading parts is carried out by separately loading paper with the first and second loading parts. And determining whether paper is loaded in the first and second loading portions when it is determined that the determination is made. The method of claim 30, wherein the step of determining whether or not the paper loading of the first and second loading portion, Determining that paper is loaded in the first loading part when the width detecting sensor is determined to be 'on'; Determining that paper is loaded in the second loading part when the second loading part paper sensor and the separate sensor are determined to be 'on'; Determining that paper is loaded in the first and second loading parts when the width detecting sensor, the second loading part paper detection sensor, and the separate sensor are determined to be 'on'; And And determining that no paper is loaded or errors in both the first and second loading portions when no sensor is 'on'. 32. The paper feed method according to claim 31, wherein the step of determining that the paper is not loaded or an error further comprises the step of warning or displaying that there is no paper or an error on the outside. 28. The method of claim 27, wherein the step of raising at least one of the first and second loading portions from the first position to the second position, Raising both the first and second loading portions from a first position to a second position when it is determined that paper is loaded simultaneously with the first and second loading portions; And And raising only the first loading portion from the first position to the second position when it is determined that paper is separately loaded in the first and second loading portions. 34. The method of claim 33, wherein the step of raising only the first loading portion from the first position to the second position when it is determined that paper is separately loaded in the first and second loading portions, Raising the first loading portion from the first position to the second position when it is determined that paper is loaded in the first loading portion or the first and second loading portions; And Moving the paper loaded in the second loading portion to the first loading portion and then raising the first loading portion from the first position to the second position when it is determined that paper is loaded in the second loading portion. And a feeding method of an image forming apparatus. 35. The method of claim 34, wherein the step of moving the paper loaded in the second loading portion to the first loading portion and then raising the first loading portion from the first position to the second position, Determining whether the side guide part is in a position where the paper loaded in the second loading part can move; Moving the sheet of the second loading portion to the first loading portion; And And raising the first loading portion from the first position to the second position. 36. The method of claim 35, wherein the step of determining whether the side guide portion is in a position to move the paper loaded in the second loading portion, Determining a separation width of the first and second side guides of the side guide part by the width detecting sensor; And And determining whether paper is to be transported according to the determined separation widths of the first and second side guides of the side guide part. 37. The method of claim 36, wherein the step of determining whether the paper is to be transported is determined that the separation widths of the first and second side guide portions of the side guide portion determined are smaller than the width of the paper loaded on the second loading portion. And alarming or displaying the same to the outside when the image forming apparatus is supplied. The method of claim 27, Determining whether the paper of the first loading part is exhausted; And And notifying the paper consumption to the outside or supplying the paper of the second loading part to the first loading part according to whether the paper of the first loading part is consumed or not. The method of claim 38, wherein the step of notifying the paper consumption to the outside or supplying the paper of the second loading portion to the first loading portion, Alarming and / or displaying a paper outward when paper is simultaneously loaded in the first and second loading portions or when it is determined that there is no paper in the second loading portion; Lowering the first loading portion from the second position to the first position when it is determined that paper is separately loaded on the first and second loading portions and there is paper on the second loading portion; Determining whether the side guide part is in a position where the paper loaded in the second loading part can move; Moving the sheet of the second loading portion to the first loading portion; And And raising the first loading portion from the first position to the second position.

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